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  • Pass Arguments to Included Module in Ruby?

    - by viatropos
    I'm hoping to implement something like all of the great plugins out there for ruby, so that you can do this: acts_as_commentable has_attached_file :avatar But I have one constraint: That helper method can only include a module; it can't define any variables or methods. The reason for this is because, I want the options hash to define something like type, and that could be converted into one of say 20 different 'workhorse' modules, all of which I could sum up in a line like this: def dynamic_method(options = {}) include ("My::Helpers::#{options[:type].to_s.camelize}").constantize(options) end Then those 'workhorses' would handle the options, doing things like: has_many "#{options[:something]}" Here's what the structure looks like, and I'm wondering if you know the missing piece in the puzzle: # 1 - The workhorse, encapsuling all dynamic variables module My::Module def self.included(base) base.extend ClassMethods base.class_eval do include InstanceMethods end end module InstanceMethods self.instance_eval %Q? def #{options[:my_method]} "world!" end ? end module ClassMethods end end # 2 - all this does is define that helper method module HelperModule def self.included(base) base.extend(ClassMethods) end module ClassMethods def dynamic_method(options = {}) # don't know how to get options through! include My::Module(options) end end end # 3 - send it to active_record ActiveRecord::Base.send(:include, HelperModule) # 4 - what it looks like class TestClass < ActiveRecord::Base dynamic_method :my_method => "hello" end puts TestClass.new.hello #=> "world!" That %Q? I'm not totally sure how to use, but I'm basically just wanting to somehow be able to pass the options hash from that helper method into the workhorse module. Is that possible? That way, the workhorse module could define all sorts of functionality, but I could name the variables whatever I wanted at runtime.

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  • Loop through a set of HTML files and append text at top and bottom of each file

    - by NJTechGuy
    For instance, I have an HTML file like this : a.htm <body> Hello world! </body> I want : a.htm <html> <LINK href='style.css' rel=stylesheet type='text/css'> <body> Hello world! </body> </html> The code I have so far is : #!/bin/sh for i in `ls *.htm` do @echo off echo ***New top line*** > temp.txt type i >> temp.txt echo ***New bottom line*** >> temp.txt move /y temp.txt i done Errors : abc@bunny:~/fileAppendText$ ./loopAllFilesTest.sh ./loopAllFilesTest.sh: line 5: @echo: command not found ./loopAllFilesTest.sh: line 7: type: i: not found ./loopAllFilesTest.sh: line 9: move: command not found ./loopAllFilesTest.sh: line 5: @echo: command not found ./loopAllFilesTest.sh: line 7: type: i: not found ./loopAllFilesTest.sh: line 9: move: command not found ./loopAllFilesTest.sh: line 5: @echo: command not found ./loopAllFilesTest.sh: line 7: type: i: not found ./loopAllFilesTest.sh: line 9: move: command not found Please help. Thanks!

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  • Call 32-bit or 64-bit program from bootloader

    - by user1002358
    There seems to be quite a lot of identical information on the Internet about writing the following 3 bootloaders: Infinite loop jmp $ Print a single character Print "Hello World". This is fantastic, and I've gone through these 3 variations with very little trouble. I'd like to write some 32- or 64-bit code in C and compile it, and call that code from the bootloader... basically a bootloader that, for example, sets the computer up to run some simple numerical simulation. I'll start by listing primes, for example, and then maybe some input/output from the user to maybe compute a Fourier transform. I don't know. I haven't found any information on how to do this, but I can already foresee some problems before I even begin. First of all, compiling a C program compiles it into one of several different files, depending on the target. For Windows, it's a PE file. For Linux, it's a .out file. These files are both quite different. In my instance, the target isn't Windows or Linux, it's just whatever I have written in the bootloader. Secondly, where would the actual code reside? The bootloader is exactly 512 bytes, but the program I write in C will certainly compile to something much larger. It will need to sit on my (virtual) hard disk, probably in some sort of file system (which I haven't even defined!) and I will need to load the information from this file into memory before I can even think about executing it. But from my understanding, all this is many, many orders of magnitude more complex than a 12-line "Hello World" bootloader. So my question is: How do I call a large 32- or 64-bit program (written in C/C++) from my 16-bit bootloader.

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  • What is the strangest programming language you have used?

    - by Anders Sandvig
    For me I think it has to be the scripting language of an old proprietary telephony platform I used in the early 2000s. The language itself was not so bad, but the fact that it was meant to be edited with a drag-and-drop GUI, which did not expose all the functionality I needed, was quite frustrating. I also remember having to manually implement many common functions, such as calculating the length of a string. Whenever I wanted to use "custom" or "advanced" functions, I had to edit the script files in a text editor, but as soon as I opened the files in the GUI again they were reformatted and restructured, which usually resulted in broken code. And, of course, this was an interpreted language, so I would not know it was broken until I actually ran it—oh, and did I mention that it did not run the same in the simulator as in the live environment? So, what is the strangest programming language or environment you have used, and why did you use it? Note that I'm interested in languages and environments that you have actually used for "real-world" situations, so Whitespace, Brainf***k and friends are not valid—unless you have used them for something "real", of course.

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  • Why use shorter VARCHAR(n) fields?

    - by chryss
    It is frequently advised to choose database field sizes to be as narrow as possible. I am wondering to what degree this applies to SQL Server 2005 VARCHAR columns: Storing 10-letter English words in a VARCHAR(255) field will not take up more storage than in a VARCHAR(10) field. Are there other reasons to restrict the size of VARCHAR fields to stick as closely as possible to the size of the data? I'm thinking of Performance: Is there an advantage to using a smaller n when selecting, filtering and sorting on the data? Memory, including on the application side (C++)? Style/validation: How important do you consider restricting colunm size to force non-sensical data imports to fail (such as 200-character surnames)? Anything else? Background: I help data integrators with the design of data flows into a database-backed system. They have to use an API that restricts their choice of data types. For character data, only VARCHAR(n) with n <= 255 is available; CHAR, NCHAR, NVARCHAR and TEXT are not. We're trying to lay down some "good practices" rules, and the question has come up if there is a real detriment to using VARCHAR(255) even for data where real maximum sizes will never exceed 30 bytes or so. Typical data volumes for one table are 1-10 Mio records with up to 150 attributes. Query performance (SELECT, with frequently extensive WHERE clauses) and application-side retrieval performance are paramount.

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  • Python - Access a class from a list using a key

    - by Fake Name
    Is there any way to make a list of classes behave like a set in python? Basically, I'm working on a piece of software that does some involved string comparison, and I have a custom class for handling the strings. Therefore, there is an instance of the class for each string. As a result, I have a large list containing all these classes. I would like to be able to access them like list[key], where in this case, the key is a string the class is based off of. It seems to me that I sould be able to do this somewhat easily, by adding something like __cmp__ to the class, but either I'm being obtuse (likely), or Im missing someting in the docs. Basically, I want to be able to do something like this (Python prompt example): >>class a: ... def __init__(self, x): ... self.var = x ... >>> from test import a >>> cl = set([a("Hello"), a("World"), a("Pie")]) >>> print cl set([<test.a instance at 0x00C866C0>, <test.a instance at 0x00C866E8>, <test.a instance at 0x00C86710>]) >>> cl["World"] <test.a instance at 0x00C866E8> Thanks!

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  • c++ simple conditional logging

    - by Sunny
    Disclaimer: I'm not a c++ developer, I can only do basic things. (I understand pointers, just my knowledge is so rusty, I haven't touch c/c++ for about 20 years :) ) The setup: I have an Outlook addin, written in C#/.Net 1.1. It uses a c++ shim to load. Usually, this works pretty well, and I use in my c# code nlog for logging purposes. But sometimes, the addin fails to load, i.t. it does not hit the managed code at all for me to be able to investigate the problem from the log files. So, I need to hook some basic logging into the c++ shim - just writing in a file. I need to make it as simple as possible for our users to enable. Actually I would prefer not to ship it by default. I was thinking about something, which will check if a specific dll is present (the logging dll), and if so, to use it. Otherwise, it will just not log anything. That way, when I have a user with such a problems, I can send him only the logging dll, the user will save it in the runtime directory, and I'll have the file. I guess this have to be done with some form a factory solution, which returns either a dummy logger, or if the dll is found, a real one. Another option would be to make some simple logger, and rebuild the shim with or w/o using it, based on directives. This is not the desirable approach, because the shim needs to be signed, and I have to instruct the user to make a backup copy of the "real" one, then restore when done, etc., instead of just saving and deleting a dll. I'd appreciate any good suggestion how to approach it, together with links or sample code how to go after this. Cheers

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  • Java JRE vs GCJ

    - by Martijn Courteaux
    Hi, I have this results from a speed test I wrote in Java: Java real 0m20.626s user 0m20.257s sys 0m0.244s GCJ real 3m10.567s user 3m5.168s sys 0m0.676s So, what is the but of GCJ then? With this results I'm sure I'm not going to compile it with GCJ! I tested this on Linux, are the results in Windows maybe better than that? This was the code from the application: public static void main(String[] args) { String str = ""; System.out.println("Start!!!"); for (long i = 0; i < 5000000L; i++) { Math.sqrt((double) i); Math.pow((double) i, 2.56); long j = i * 745L; String string = new String(String.valueOf(i)); string = string.concat(" kaka pipi"); // "Kaka pipi" is a kind of childly call in Dutch. string = new String(string.toUpperCase()); if (i % 300 == 0) { str = ""; } else { str += Long.toHexString(i); } } System.out.println("Stop!!!"); }

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  • Context path routing in Tomcat ( service swapping )

    - by jojovilco
    Here is what I would like to achieve: I have a web service A which I want to be able to deploy side by side with other web services of type A - different version(s). For now I assume 2 instances side by side. I need it because the service has a warm up stage, which takes some time to build up stuff from DB and only after it is ready it can start serving requests ... I was thinking to deploy to Tomcat context paths like: "/ServiceA-1.0", "/ServiceA-2.0" and then have a "virtual" context like "/ServiceA" which will point to the desired physical service e.g. "/ServiceA-1.0". So external world will know about ServiceA, but internally, my ServiceA related stack would know about versioned ServiceA url ( there are more components involved but only ServiceA is serving outer world ). When new service is ready, I would just reconfigure the "virtual" context to point to a new service. So far, I was not able to find out how to do this with Tomcat and starting to tkink it is not possible. I found suggestions to place Apache Server in front of Tomcat and do the routing there, but I do not want to enroll another piece of software unless necessary. My questions are: - is this kind of a "virtual" context and routing possible to do with Tomcat? - any other options, wisdom and lessons learned how to achieve this kind of service swapping scenario? Best, Jozef

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  • Binding Javascript Event Handlers to a an Ajax HTML Response?

    - by John
    Let's say I have the following HTML code <div id="outer"> <div id="inner">Hello World</div> </div> At the end of my HTML page, I use javascript to attach event handlers like so, document.getElementById('inner').onclick = function() {alert(this.innerHTML);} document.getElementById('outer').onclick = function() { /* An Ajax Call where the response, which will be a string of HTML content, then goes into document.getElementById('outer').innerHTML */ document.getElementById('inner').onclick = function() {alert(this.innerHTML);} } In the above code, I am expecting <div id="inner">Hello World 2</div> to come back which requires me to re-attach the onclick event handler. This makes sense because the new response coming back is just a string, and I have to tell the browser that after converting to DOM, i also need some event handlers So my question is, is there a better way to manage event handlers on AJAX response that contains HTML content? I could use inline javascript within the html response, but then it prevents me from achieving non-intrusive javascript. So is there a way to achieve non-intrusive javascript and an efficient way to "maintain" event handlers of ajax html responses?

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  • Python "callable" attribute (pseudo-property)

    - by mgilson
    In python, I can alter the state of an instance by directly assigning to attributes, or by making method calls which alter the state of the attributes: foo.thing = 'baz' or: foo.thing('baz') Is there a nice way to create a class which would accept both of the above forms which scales to large numbers of attributes that behave this way? (Shortly, I'll show an example of an implementation that I don't particularly like.) If you're thinking that this is a stupid API, let me know, but perhaps a more concrete example is in order. Say I have a Document class. Document could have an attribute title. However, title may want to have some state as well (font,fontsize,justification,...), but the average user might be happy enough just setting the title to a string and being done with it ... One way to accomplish this would be to: class Title(object): def __init__(self,text,font='times',size=12): self.text = text self.font = font self.size = size def __call__(self,*text,**kwargs): if(text): self.text = text[0] for k,v in kwargs.items(): setattr(self,k,v) def __str__(self): return '<title font={font}, size={size}>{text}</title>'.format(text=self.text,size=self.size,font=self.font) class Document(object): _special_attr = set(['title']) def __setattr__(self,k,v): if k in self._special_attr and hasattr(self,k): getattr(self,k)(v) else: object.__setattr__(self,k,v) def __init__(self,text="",title=""): self.title = Title(title) self.text = text def __str__(self): return str(self.title)+'<body>'+self.text+'</body>' Now I can use this as follows: doc = Document() doc.title = "Hello World" print (str(doc)) doc.title("Goodbye World",font="Helvetica") print (str(doc)) This implementation seems a little messy though (with __special_attr). Maybe that's because this is a messed up API. I'm not sure. Is there a better way to do this? Or did I leave the beaten path a little too far on this one? I realize I could use @property for this as well, but that wouldn't scale well at all if I had more than just one attribute which is to behave this way -- I'd need to write a getter and setter for each, yuck.

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  • Set the background color for a fixed range of cells

    - by Count Boxer
    I have VBA code in an Excel spreadsheet. It is used to set the font and background color of a cell based on the value in that cell. I am doing it in VBA instead of "Conditional Formatting" because I have more than 3 conditions. The code is: Private Sub Worksheet_Change(ByVal Target As Range) Dim c As Range, d As Range, fc As Long, bc As Long, bf As Boolean Set d = Intersect(Range("A:K"), Target) If d Is Nothing Then Exit Sub For Each c In d If c >= Date And c <= Date + 5 Then fc = 2: fb = True: bc = 3 Else Select Case c Case "ABC" fc = 2: fb = True: bc = 5 Case 1, 3, 5, 7 fc = 2: fb = True: bc = 1 Case "D", "E", "F" fc = 2: fb = True: bc = 10 Case "1/1/2009" fc = 2: fb = True: bc = 45 Case "Long string" fc = 3: fb = True: bc = 1 Case Else fc = 1: fb = False: bc = xlNone End Select End If c.Font.ColorIndex = fc c.Font.Bold = fb c.Interior.ColorIndex = bc c.Range("A1:D1").Interior.ColorIndex = bc Next End Sub The problem is in the "c.Range" line. It always uses the current cell as "A" and then goes four cells to the right. I want it to start in the "real" cell "A" of the current row and go to the "real" cell "D" of the current row. Basically, I want a fixed range and not a dynamic one.

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  • Are reads and (transactional) writes faster for entities of the same group than otherwise?

    - by indiehacker
    What advantage is there to designing child-parent relationships, which allow us to do writes in transactions, when there is never a real concern for consistency and contention and those sort of more complex issues? Does it make writes and reads faster? Consider my situation where there are many .png images that are referenced to one mosaic layer, and these .png images are written just once by a single user. The user can design many mosaic layers and her mosaic layers and referenced image entities are never changed/updated, they are just deleted some time in the future. Other users can come to the web project site and interactively view the mosaic layer as different layouts/configurations of the images as they play (query) with different criteria. So reads should be very fast. So there is no real worry of contention, or users conflicting with one another with writing new image entities. And because of that I am assuming there is no "requirement" for the .png image entities to be grouped by their same mosaic layer in child-parent relationship. However, perhaps, since the documentation says they are stored close to one another, if the many image entities were grouped as children to a single mosaic layer parent than this has the advantage that the writing (in transaction) and reading will happen much faster?

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  • Cannot see echo message but my localhost works

    - by Sean
    This is my very first php code and I can't seem to get it to work. (I'm using Eclipse) <html> <body> <?php echo 'Hello World!'; $txt = "I <3 you!"; $num = 19; ?> </html> </body> When I run it (http://localhost/Assignment3.0/index.php), I get: Not Found The requested URL /Assignment3.0/index.php was not found on this server. Apache/2.2.22 (Ubuntu) Server at localhost Port 80 But when I run this (http://localhost/), I get: It works! This is the default web page for this server. The web server software is running but no content has been added, yet. So what could be the problem? Where's my "Hello World!"? Also, for Stackoverflow formatting, how do I start a new line w/o adding a blank line in between?

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  • Embedded Development Board

    - by ALF3130
    I'm new to the embedded development world and am looking to get my very first board. After some research, I realize that there aren't many choices with FPUs. This is important in my project as I'm going to be doing quite a bit of floating point computations. I found the Mini2440 which seems to run on the ARM920T core. This particular unit is perfect for my needs (decent price, all the right I/O ports, and a touch screen to boot) but it seems that it doesn't have an FPU. I don't know how big of a penalty I'd be paying for FP emulation, so I'm unsure of whether to pull the trigger on this one. That said: Can someone please confirm whether this product (Mini2440) has an FPU or not? My project will do image capture and analysis. Does anyone have any experience with running things like OpenMP on such platforms? Please suggest any other similar boards in the = $200 price range that have an FPU. This world is new to me. Any other advice or things I should be aware of is much appreciated.

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  • SQL Server: Why use shorter VARCHAR(n) fields?

    - by chryss
    It is frequently advised to choose database field sizes to be as narrow as possible. I am wondering to what degree this applies to SQL Server 2005 VARCHAR columns: Storing 10-letter English words in a VARCHAR(255) field will not take up more storage than in a VARCHAR(10) field. Are there other reasons to restrict the size of VARCHAR fields to stick as closely as possible to the size of the data? I'm thinking of Performance: Is there an advantage to using a smaller n when selecting, filtering and sorting on the data? Memory, including on the application side (C++)? Style/validation: How important do you consider restricting colunm size to force non-sensical data imports to fail (such as 200-character surnames)? Anything else? Background: I help data integrators with the design of data flows into a database-backed system. They have to use an API that restricts their choice of data types. For character data, only VARCHAR(n) with n <= 255 is available; CHAR, NCHAR, NVARCHAR and TEXT are not. We're trying to lay down some "good practices" rules, and the question has come up if there is a real detriment to using VARCHAR(255) even for data where real maximum sizes will never exceed 30 bytes or so. Typical data volumes for one table are 1-10 Mio records with up to 150 attributes. Query performance (SELECT, with frequently extensive WHERE clauses) and application-side retrieval performance are paramount.

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  • overload == (and != , of course) operator, can I bypass == to determine whether the object is null

    - by LLS
    Hello, when I try to overload operator == and != in C#, and override Equal as recommended, I found I have no way to distinguish a normal object and null. For example, I defined a class Complex. public static bool operator ==(Complex lhs, Complex rhs) { return lhs.Equals(rhs); } public static bool operator !=(Complex lhs, Complex rhs) { return !lhs.Equals(rhs); } public override bool Equals(object obj) { if (obj is Complex) { return (((Complex)obj).Real == this.Real && ((Complex)obj).Imaginary == this.Imaginary); } else { return false; } } But when I want to use if (temp == null) When temp is really null, some exception happens. And I can't use == to determine whether the lhs is null, which will cause infinite loop. What should I do in this situation. One way I can think of is to us some thing like Class.Equal(object, object) (if it exists) to bypass the == when I do the check. What is the normal way to solve the problem?

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  • QLearning and never-ending episodes

    - by devoured elysium
    Let's imagine we have an (x,y) plane where a robot can move. Now we define the middle of our world as the goal state, which means that we are going to give a reward of 100 to our robot once it reaches that state. Now, let's say that there are 4 states(which I will call A,B,C,D) that can lead to the goal state. The first time we are in A and go to the goal state, we will update our QValues table as following: Q(state = A, action = going to goal state) = 100 + 0 One of 2 things can happen. I can end the episode here, and start a different one where the robot has to find again the goal state, or I can continue exploring the world even after I found the goal state. If I try to do this, I see a problem though. If I am in the goal state and go back to state A, it's Qvalue will be the following: Q(state = goalState, action = going to A) = 0 + gamma * 100 Now, if I try to go again to the goal state from A: Q(state = A, action = going to goal state) = 100 + gamma * (gamma * 100) Which means that if I keep doing this, as 0 <= gamma <= 0, both qValues are going to rise forever. Is this the expected behavior of QLearning? Am I doing something wrong? If this is the expected behavior, can't this lead to problems? I know that probabilistically, all the 4 states(A,B,C and D), will grow at the same rate, but even so it kinda bugs me having them growing forever. The ideia of allowing the agent to continue exploring even after finding the goal has to do with that the nearer he is from the goal state, the more likely it is to being in states that can be updated at the moment.

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  • Is my approach for persistent login secure ?

    - by Jay
    I'm very much stuck with the reasonable secure approach to implement 'Remember me' feature in a login system. Here's my approach so far, Please advice me if it makes sense and is reasonably secure: Logging: User provides email and password to login (both are valid).. Get the user_id from DB Table Users by comparing provided email Generate 2 random numbers hashed strings: key1, key2 and store in cookies. In DB Table COOKIES, store key1, key2 along with user_id. To Check login: If key1 and key2 both cookies exist, validate both keys in DB Table COOKIES (if a row with key1, and key2 exists, user is logged). if cookie is valid, regenrate key2 and update it in cookie and also database. Why re-genrating key: Because if someone steals cookie and login with that cookie, it will be working only until the real user login. When the real user will login, the stolen cookie will become invalid. Right? Why do I need 2 keys: Because if i store user_id and single key in cookie and database, and the user want to remember the password on another browser, or computer, then the new key will be updated in database, so the user's cookie in earlier browser/PC will become invalid. User wont be able to remember password on more than one place. Thanks for your opinions.

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  • Taking item from string array that *might* be there

    - by AndyC
    Hi all, I have a string array, and it may contain an element with the text "mytext" within the string. eg: mystringarray { [0] => "hello world"; [1] => "some of mytext"; } I also have an array that doesn't have the mytext text in it. mystringarray { [0] => "hello world"; [1] => "some of notmy"; } My problem is when I use: string mytextdata = mystringarray.Single<string>(t => t.Contains("mytext")).ToString(); I get an exception for the second array as it can't find an element that matches the expression. Is there a quick way I can edit this one line to not throw an exception if it finds nothing, and instead just ignore? I have a lot of these lines and I don't want to have to wrap each in an if statement. Apologies if question isn't clear.

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  • What are advantages of using a one-to-one table relationship? (MySQL)

    - by byronh
    What are advantages of using a one-to-one table relationship as opposed to simply storing all the data in one table? I understand and make use of one-to-many, many-to-one, and many-to-many all the time, but implementing a one-to-one relationship seems like a tedious and unnecessary task, especially if you use naming conventions for relating (php) objects to database tables. I couldn't find anything on the net or on this site that could supply a good real-world example of a one-to-one relationship. At first I thought it might be logical to separate 'users', for example, into two tables, one containing public information like an 'about me' for profile pages and one containing private information such as login/password, etc. But why go through all the trouble of using unnecessary JOINS when you can just choose which fields to select from that table anyway? If I'm displaying the user's profile page, obviously I would only SELECT id,username,email,aboutme etc. and not the fields containing their private info. Anyone care to enlighten me with some real-world examples of one-to-one relationships?

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  • Finding k elements of length-n list that sum to less than t in O(nlogk) time

    - by tresbot
    This is from Programming Pearls ed. 2, Column 2, Problem 8: Given a set of n real numbers, a real number t, and an integer k, how quickly can you determine whether there exists a k-element subset of the set that sums to at most t? One easy solution is to sort and sum the first k elements, which is our best hope to find such a sum. However, in the solutions section Bentley alludes to a solution that takes nlog(k) time, though he gives no hints for how to find it. I've been struggling with this; one thought I had was to go through the list and add all the elements less than t/k (in O(n) time); say there are m1 < k such elements, and they sum to s1 < t. Then we are left needing k - m1 elements, so we can scan through the list again in O(n) time looking for all elements less than (t - s1)/(k - m1). Add in again, to get s2 and m2, then again if m2 < k, look for all elements less than (t - s2)/(k - m2). So: def kSubsetSumUnderT(inList, k, t): outList = [] s = 0 m = 0 while len(outList) < k: toJoin = [i for i in inList where i < (t - s)/(k - m)] if len(toJoin): if len(toJoin) >= k - m: toJoin.sort() if(s0 + sum(toJoin[0:(k - m - 1)]) < t: return True return False outList = outList + toJoin s += sum(toJoin) m += len(toJoin) else: return False My intuition is that this might be the O(nlog(k)) algorithm, but I am having a hard time proving it to myself. Thoughts?

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  • Question about SharedPreferences

    - by chobo2
    I am looking an android Shared Preferences and I am wondering is there a way to just check if the preferences file exists. SharedPreferences mySharedPreferences ; mySharedPreferences=getSharedPreferences(“Name_of_your_preference”,mode); This above code leads me to believe that "Name_of_Your_preferene" is stored as a file or some sort of container that will contain your preferences. I am wondering is there away to check if this exists or not. When a user loads up an activity I want to save all the settings into this file with some default values(off for all settings). However I only want to do this if they are going to the page for the first time. Otherwise if I would do something like this every time the page loads up SharedPreferences.Editor editor= mySharedPreferences.edit(); /* now store your primitive type values. In this case it is true, 1f and Hello! World */ editor.putBolean(“myBoolean”,true); editor.putFloat(“myFloat”,1f); editor.putString(“myString”,” Hello! World”); I am guessing it would override all settings even ones they set.

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  • Announcing the Release of Visual Studio 2013 and Great Improvements to ASP.NET and Entity Framework

    - by ScottGu
    Today we released VS 2013 and .NET 4.5.1. These releases include a ton of great improvements, and include some fantastic enhancements to ASP.NET and the Entity Framework.  You can download and start using them now. Below are details on a few of the great ASP.NET, Web Development, and Entity Framework improvements you can take advantage of with this release.  Please visit http://www.asp.net/vnext for additional release notes, documentation, and tutorials. One ASP.NET With the release of Visual Studio 2013, we have taken a step towards unifying the experience of using the different ASP.NET sub-frameworks (Web Forms, MVC, Web API, SignalR, etc), and you can now easily mix and match the different ASP.NET technologies you want to use within a single application. When you do a File-New Project with VS 2013 you’ll now see a single ASP.NET Project option: Selecting this project will bring up an additional dialog that allows you to start with a base project template, and then optionally add/remove the technologies you want to use in it.  For example, you could start with a Web Forms template and add Web API or Web Forms support for it, or create a MVC project and also enable Web Forms pages within it: This makes it easy for you to use any ASP.NET technology you want within your apps, and take advantage of any feature across the entire ASP.NET technology span. Richer Authentication Support The new “One ASP.NET” project dialog also includes a new Change Authentication button that, when pushed, enables you to easily change the authentication approach used by your applications – and makes it much easier to build secure applications that enable SSO from a variety of identity providers.  For example, when you start with the ASP.NET Web Forms or MVC templates you can easily add any of the following authentication options to the application: No Authentication Individual User Accounts (Single Sign-On support with FaceBook, Twitter, Google, and Microsoft ID – or Forms Auth with ASP.NET Membership) Organizational Accounts (Single Sign-On support with Windows Azure Active Directory ) Windows Authentication (Active Directory in an intranet application) The Windows Azure Active Directory support is particularly cool.  Last month we updated Windows Azure Active Directory so that developers can now easily create any number of Directories using it (for free and deployed within seconds).  It now takes only a few moments to enable single-sign-on support within your ASP.NET applications against these Windows Azure Active Directories.  Simply choose the “Organizational Accounts” radio button within the Change Authentication dialog and enter the name of your Windows Azure Active Directory to do this: This will automatically configure your ASP.NET application to use Windows Azure Active Directory and register the application with it.  Now when you run the app your users can easily and securely sign-in using their Active Directory credentials within it – regardless of where the application is hosted on the Internet. For more information about the new process for creating web projects, see Creating ASP.NET Web Projects in Visual Studio 2013. Responsive Project Templates with Bootstrap The new default project templates for ASP.NET Web Forms, MVC, Web API and SPA are built using Bootstrap. Bootstrap is an open source CSS framework that helps you build responsive websites which look great on different form factors such as mobile phones, tables and desktops. For example in a browser window the home page created by the MVC template looks like the following: When you resize the browser to a narrow window to see how it would like on a phone, you can notice how the contents gracefully wrap around and the horizontal top menu turns into an icon: When you click the menu-icon above it expands into a vertical menu – which enables a good navigation experience for small screen real-estate devices: We think Bootstrap will enable developers to build web applications that work even better on phones, tablets and other mobile devices – and enable you to easily build applications that can leverage the rich ecosystem of Bootstrap CSS templates already out there.  You can learn more about Bootstrap here. Visual Studio Web Tooling Improvements Visual Studio 2013 includes a new, much richer, HTML editor for Razor files and HTML files in web applications. The new HTML editor provides a single unified schema based on HTML5. It has automatic brace completion, jQuery UI and AngularJS attribute IntelliSense, attribute IntelliSense Grouping, and other great improvements. For example, typing “ng-“ on an HTML element will show the intellisense for AngularJS: This support for AngularJS, Knockout.js, Handlebars and other SPA technologies in this release of ASP.NET and VS 2013 makes it even easier to build rich client web applications: The screen shot below demonstrates how the HTML editor can also now inspect your page at design-time to determine all of the CSS classes that are available. In this case, the auto-completion list contains classes from Bootstrap’s CSS file. No more guessing at which Bootstrap element names you need to use: Visual Studio 2013 also comes with built-in support for both CoffeeScript and LESS editing support. The LESS editor comes with all the cool features from the CSS editor and has specific Intellisense for variables and mixins across all the LESS documents in the @import chain. Browser Link – SignalR channel between browser and Visual Studio The new Browser Link feature in VS 2013 lets you run your app within multiple browsers on your dev machine, connect them to Visual Studio, and simultaneously refresh all of them just by clicking a button in the toolbar. You can connect multiple browsers (including IE, FireFox, Chrome) to your development site, including mobile emulators, and click refresh to refresh all the browsers all at the same time.  This makes it much easier to easily develop/test against multiple browsers in parallel. Browser Link also exposes an API to enable developers to write Browser Link extensions.  By enabling developers to take advantage of the Browser Link API, it becomes possible to create very advanced scenarios that crosses boundaries between Visual Studio and any browser that’s connected to it. Web Essentials takes advantage of the API to create an integrated experience between Visual Studio and the browser’s developer tools, remote controlling mobile emulators and a lot more. You will see us take advantage of this support even more to enable really cool scenarios going forward. ASP.NET Scaffolding ASP.NET Scaffolding is a new code generation framework for ASP.NET Web applications. It makes it easy to add boilerplate code to your project that interacts with a data model. In previous versions of Visual Studio, scaffolding was limited to ASP.NET MVC projects. With Visual Studio 2013, you can now use scaffolding for any ASP.NET project, including Web Forms. When using scaffolding, we ensure that all required dependencies are automatically installed for you in the project. For example, if you start with an ASP.NET Web Forms project and then use scaffolding to add a Web API Controller, the required NuGet packages and references to enable Web API are added to your project automatically.  To do this, just choose the Add->New Scaffold Item context menu: Support for scaffolding async controllers uses the new async features from Entity Framework 6. ASP.NET Identity ASP.NET Identity is a new membership system for ASP.NET applications that we are introducing with this release. ASP.NET Identity makes it easy to integrate user-specific profile data with application data. ASP.NET Identity also allows you to choose the persistence model for user profiles in your application. You can store the data in a SQL Server database or another data store, including NoSQL data stores such as Windows Azure Storage Tables. ASP.NET Identity also supports Claims-based authentication, where the user’s identity is represented as a set of claims from a trusted issuer. Users can login by creating an account on the website using username and password, or they can login using social identity providers (such as Microsoft Account, Twitter, Facebook, Google) or using organizational accounts through Windows Azure Active Directory or Active Directory Federation Services (ADFS). To learn more about how to use ASP.NET Identity visit http://www.asp.net/identity.  ASP.NET Web API 2 ASP.NET Web API 2 has a bunch of great improvements including: Attribute routing ASP.NET Web API now supports attribute routing, thanks to a contribution by Tim McCall, the author of http://attributerouting.net. With attribute routing you can specify your Web API routes by annotating your actions and controllers like this: OAuth 2.0 support The Web API and Single Page Application project templates now support authorization using OAuth 2.0. OAuth 2.0 is a framework for authorizing client access to protected resources. It works for a variety of clients including browsers and mobile devices. OData Improvements ASP.NET Web API also now provides support for OData endpoints and enables support for both ATOM and JSON-light formats. With OData you get support for rich query semantics, paging, $metadata, CRUD operations, and custom actions over any data source. Below are some of the specific enhancements in ASP.NET Web API 2 OData. Support for $select, $expand, $batch, and $value Improved extensibility Type-less support Reuse an existing model OWIN Integration ASP.NET Web API now fully supports OWIN and can be run on any OWIN capable host. With OWIN integration, you can self-host Web API in your own process alongside other OWIN middleware, such as SignalR. For more information, see Use OWIN to Self-Host ASP.NET Web API. More Web API Improvements In addition to the features above there have been a host of other features in ASP.NET Web API, including CORS support Authentication Filters Filter Overrides Improved Unit Testability Portable ASP.NET Web API Client To learn more go to http://www.asp.net/web-api/ ASP.NET SignalR 2 ASP.NET SignalR is library for ASP.NET developers that dramatically simplifies the process of adding real-time web functionality to your applications. Real-time web functionality is the ability to have server-side code push content to connected clients instantly as it becomes available. SignalR 2.0 introduces a ton of great improvements. We’ve added support for Cross-Origin Resource Sharing (CORS) to SignalR 2.0. iOS and Android support for SignalR have also been added using the MonoTouch and MonoDroid components from the Xamarin library (for more information on how to use these additions, see the article Using Xamarin Components from the SignalR wiki). We’ve also added support for the Portable .NET Client in SignalR 2.0 and created a new self-hosting package. This change makes the setup process for SignalR much more consistent between web-hosted and self-hosted SignalR applications. To learn more go to http://www.asp.net/signalr. ASP.NET MVC 5 The ASP.NET MVC project templates integrate seamlessly with the new One ASP.NET experience and enable you to integrate all of the above ASP.NET Web API, SignalR and Identity improvements. You can also customize your MVC project and configure authentication using the One ASP.NET project creation wizard. The MVC templates have also been updated to use ASP.NET Identity and Bootstrap as well. An introductory tutorial to ASP.NET MVC 5 can be found at Getting Started with ASP.NET MVC 5. This release of ASP.NET MVC also supports several nice new MVC-specific features including: Authentication filters: These filters allow you to specify authentication logic per-action, per-controller or globally for all controllers. Attribute Routing: Attribute Routing allows you to define your routes on actions or controllers. To learn more go to http://www.asp.net/mvc Entity Framework 6 Improvements Visual Studio 2013 ships with Entity Framework 6, which bring a lot of great new features to the data access space: Async and Task<T> Support EF6’s new Async Query and Save support enables you to perform asynchronous data access and take advantage of the Task<T> support introduced in .NET 4.5 within data access scenarios.  This allows you to free up threads that might otherwise by blocked on data access requests, and enable them to be used to process other requests whilst you wait for the database engine to process operations. When the database server responds the thread will be re-queued within your ASP.NET application and execution will continue.  This enables you to easily write significantly more scalable server code. Here is an example ASP.NET WebAPI action that makes use of the new EF6 async query methods: Interception and Logging Interception and SQL logging allows you to view – or even change – every command that is sent to the database by Entity Framework. This includes a simple, human readable log – which is great for debugging – as well as some lower level building blocks that give you access to the command and results. Here is an example of wiring up the simple log to Debug in the constructor of an MVC controller: Custom Code-First Conventions The new Custom Code-First Conventions enable bulk configuration of a Code First model – reducing the amount of code you need to write and maintain. Conventions are great when your domain classes don’t match the Code First conventions. For example, the following convention configures all properties that are called ‘Key’ to be the primary key of the entity they belong to. This is different than the default Code First convention that expects Id or <type name>Id. Connection Resiliency The new Connection Resiliency feature in EF6 enables you to register an execution strategy to handle – and potentially retry – failed database operations. This is especially useful when deploying to cloud environments where dropped connections become more common as you traverse load balancers and distributed networks. EF6 includes a built-in execution strategy for SQL Azure that knows about retryable exception types and has some sensible – but overridable – defaults for the number of retries and time between retries when errors occur. Registering it is simple using the new Code-Based Configuration support: These are just some of the new features in EF6. You can visit the release notes section of the Entity Framework site for a complete list of new features. Microsoft OWIN Components Open Web Interface for .NET (OWIN) defines an open abstraction between .NET web servers and web applications, and the ASP.NET “Katana” project brings this abstraction to ASP.NET. OWIN decouples the web application from the server, making web applications host-agnostic. For example, you can host an OWIN-based web application in IIS or self-host it in a custom process. For more information about OWIN and Katana, see What's new in OWIN and Katana. Summary Today’s Visual Studio 2013, ASP.NET and Entity Framework release delivers some fantastic new features that streamline your web development lifecycle. These feature span from server framework to data access to tooling to client-side HTML development.  They also integrate some great open-source technology and contributions from our developer community. Download and start using them today! Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • Imperative Programming v/s Declarative Programming v/s Functional Programming

    - by kaleidoscope
    Imperative Programming :: Imperative programming is a programming paradigm that describes computation in terms of statements that change a program state. In much the same way as the imperative mood in natural languages expresses commands to take action, imperative programs define sequences of commands for the computer to perform. The focus is on what steps the computer should take rather than what the computer will do (ex. C, C++, Java). Declarative Programming :: Declarative programming is a programming paradigm that expresses the logic of a computation without describing its control flow. It attempts to minimize or eliminate side effects by describing what the program should accomplish, rather than describing how to go about accomplishing it. The focus is on what the computer should do rather than how it should do it (ex. SQL). A  C# example of declarative v/s. imperative programming is LINQ. With imperative programming, you tell the compiler what you want to happen, step by step. For example, let's start with this collection, and choose the odd numbers: List<int> collection = new List<int> { 1, 2, 3, 4, 5 }; With imperative programming, we'd step through this, and decide what we want: List<int> results = new List<int>(); foreach(var num in collection) {     if (num % 2 != 0)           results.Add(num); } Here’s what we are doing: *Create a result collection *Step through each number in the collection *Check the number, if it's odd, add it to the results With declarative programming, on the other hand, we write the code that describes what you want, but not necessarily how to get it var results = collection.Where( num => num % 2 != 0); Here, we're saying "Give us everything where it's odd", not "Step through the collection. Check this item, if it's odd, add it to a result collection." Functional Programming :: Functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions.Functional programming has its roots in the lambda calculus. It is a subset of declarative languages that has heavy focus on recursion. Functional programming can be a mind-bender, which is one reason why Lisp, Scheme, and Haskell have never really surpassed C, C++, Java and COBOL in commercial popularity. But there are benefits to the functional way. For one, if you can get the logic correct, functional programming requires orders of magnitude less code than imperative programming. That means fewer points of failure, less code to test, and a more productive (and, many would say, happier) programming life. As systems get bigger, this has become more and more important. To know more : http://stackoverflow.com/questions/602444/what-is-functional-declarative-and-imperative-programming http://msdn.microsoft.com/en-us/library/bb669144.aspx http://en.wikipedia.org/wiki/Imperative_programming   Technorati Tags: Ranjit,Imperative Programming,Declarative programming,Functional Programming

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